WO2006051600A1

WO2006051600A1 - Phosphor for display device, manufacturing method thereof and display device using the phosphor

Info

Publication number: WO2006051600A1
Application number: PCT/JP2004/016859
Authority: WO
Inventors: Shuniti Kubota; Masahiko Shimada; Kenichi Yamaguchi; Takeo Ito; Susumu Matsuura
Original assignee: Kabushiki Kaisha Toshiba
Priority date: 2004-11-12
Filing date: 2004-11-12
Publication date: 2006-05-18

Abstract

In a phosphor for display device, an area of a shorter wavelength than a wavelength 60nm shorter than a peak wavelength in emission spectrum is permitted to be 1.6% of the entire area of the spectrum or less. The phosphor can be obtained by removing adsorbed water and oxygen from a phosphor material and heating and burning the material by maintaining such status. In the phosphor to be used in color display devices such as CRT and FED, especially a green light emitting zinc sulfide phosphor, unnecessary emission due to a defect under a high current density is suppressed, and current characteristics and color purity of the color display devices are improved.

Description

Fluorescent substance for display device, manufacturing method thereof, and display device using the same

The present invention relates to a phosphor for a display device that emits light by electron beam excitation, a method for manufacturing the same, and a color display device using the same.

Background art

[0002] With the advent of the multimedia era, display devices that are the core devices of digital networks are required to have larger screens, higher definition, and compatibility with various sources such as computers. Devices using cathode ray tubes (CRT) are widely used. Regarding CRT, high-definition televisions and high-definition display tubes have been developed, and large screens and high-quality images have been improved.

[0003] Further, research and development of a field emission display device (FED) using an electron emission element such as a field emission cold cathode has been promoted as a thin display device replacing CRT. FED has the same basic display principle as CRT. In addition to basic display performance such as brightness, contrast, and color reproducibility, it has a wide viewing angle, fast response speed, and low power consumption. It has the characteristics of.

[0004] Display devices such as CRT and FED described above have a phosphor layer containing phosphors of blue light emission, green light emission and red light emission in order to enable full color display. As the blue light-emitting phosphor and the green light-emitting phosphor for these display devices, phosphors based on zinc sulfide (ZnS) are used!

[0005] For example, as a blue light emitting phosphor, ZnS phosphor containing ZnS containing Ag as a first activator and A1 or C1 as a second activator (For example, see Patent Document 1) However, as a green light emitting phosphor, ZnS contains Cu and Au as the first activator, and A1 as the second activator. Zinc sulfate phosphor is used. (For example, see Patent Document 2)

[0006] However, the phosphors described in Patent Document 1 and Patent Document 2 are not sufficiently satisfactory in color purity (chromaticity) and luminance of light emission, and green light emission with particularly high visual sensitivity. There is a demand for enhancing the luminance while enhancing the color purity of the phosphor.

[0007] In addition, as the display device becomes more precise and has higher quality, the phosphor is excited by an electron beam having a higher current density. As a result, the current characteristics of the phosphor are further improved. There is a need to improve and increase brightness at high current densities.

Patent Document 1: JP-A-62-95378 (Page 1-2)

Patent Document 2: JP-A-2002-226847 (Page 2-3)

Disclosure of the invention

[0008] The present invention has been made in order to cope with such a problem. In a green light emitting phosphor used in a power display device such as a CRT or FED, the emission chromaticity is improved and the current density is reduced. The purpose is to improve luminance and color purity in It is another object of the present invention to provide a color display device with improved display characteristics by using such a phosphor for display device.

[0009] The present inventors have studied the firing atmosphere for the phosphor matrix (for example, zinc sulfite) in order to improve the current characteristics of the green light-emitting phosphor used in a display device such as a CRT. By removing the oxygen and water remaining inside the firing material and the heat-resistant container containing the firing material, and by performing firing without maintaining the state of such residual oxygen and water, the color purity In addition, the present inventors have found that the luminance can be improved, and in particular, the current characteristics can be improved.

[0010] Display device for the phosphor of the present invention have the general formula: ZnS: Cua, Alb (where, a and b, with respect to zinc sulfide lg is a fluorescent substance matrix, 1 X 10- ⁵ ≤a ≤ has a composition substantially represented ^{1 X 10- 3 g, 1 X} 10- 5 ≤b≤5 X 10 one ³ g of a range of amounts, respectively shown), green which emits light by excitation by an electron beam It is a light emitting phosphor, and in the emission spectrum, when (O) is the area of the shorter wavelength portion than the wavelength 60 nm shorter than the wavelength at which the maximum emission intensity is obtained (hereinafter referred to as the emission peak wavelength), The ratio of the above (O) to the area (M) of the entire emission spectrum is 1.6% or less.

[0011] The method for producing a phosphor for a display device according to the present invention is a method for producing a green light-emitting phosphor containing zinc sulfide as a base and Cu and A1 as activators, respectively. And an element constituting the activator or a compound containing the element. A step of removing adsorbed moisture and oxygen from the contained phosphor material, and a step of heating and firing the phosphor material while maintaining the state where the moisture and oxygen are removed. Features.

In the method for producing a phosphor for a display device of the present invention, the step of firing the phosphor material can be performed in a sulfur atmosphere or a reducing atmosphere of 1 atm or higher.

Furthermore, the display device of the present invention includes a phosphor layer including a blue light-emitting phosphor layer, a green light-emitting phosphor layer, and a red light-emitting phosphor layer, and emitting light by irradiating the phosphor layer with an electron beam. A display device comprising: an electron source to be emitted; and an envelope for vacuum-sealing the electron source and the phosphor layer, wherein the green light-emitting phosphor layer includes the phosphor for the display device described above. The

[0014] According to the phosphor for display device of the present invention, the efficiency of green light emission can be increased by suppressing the light emission itself on the short wavelength side having a high transition probability at a high current density. As a result, the green phosphor As a result, the color purity can be increased. Therefore, according to a color display device such as a CRT or FED using such a phosphor as a green light-emitting phosphor, high luminance can be obtained.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a configuration example of a field emission display (FED) according to an embodiment of the present invention.

FIG. 2 is a graph showing emission spectra of the phosphor layers obtained in Examples and Comparative Examples of the present invention.

FIG. 3 is a graph showing the relationship between the X value and the y value of emission chromaticity in the phosphor layers obtained in the examples and comparative examples of the present invention.

FIG. 4 is a graph showing changes in luminance according to changes in current density in the phosphor layers obtained in Examples and Comparative Examples of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a preferred embodiment of the present invention will be described. The present invention is not limited to the following embodiment.

[0017] In the first embodiment of the present invention, ZnS is used as a base material, and Cu and A1 are used as activators. A green-emitting phosphor having a composition substantially represented by the general formula: ZnS: Cu, A1 is contained.

[0018] In this green emitting phosphor, Cu is a first activator which forms the luminescence center (main activator), with respect to lg of ZnS is a fluorescent substance matrix, 1 X 10- ⁵ - it is preferably contained in the range of 1 X 10- ³ g. Be less than 1 X 10 ^"5 g with respect to the content force ¾nSlg of Cu, which is the first activator, and also beyond the 1 X 10- ³ g, emission luminance and emission chromaticity is reduced. the Cu content, 3 X 10- ⁵ relative ZnSlg - 8 X 10- ⁴ g, preferably in more preferred gestures et al in the range of ^{5 X 10- 5 - 5 X 10-} 4 g range It is.

[0019] A1 is a second activator (co-activator) that is directly excited by an electron beam, and the first activator emits light with the excitation energy of the second activator. As a result, the luminance of the zinc sulfide phosphor (ZnS: Cu phosphor) can be increased. The content of the second is an activator A1, relative to lg of ZnS is a fluorescent substance matrix, 1 X 10- ⁵ - to preferably contained in the range of 5 X 10- ³ g. Also the content of A1 is less than 1 X 10- ⁵ g with respect ZnSlg, also exceed 5 X 10- ³ g, emission luminance is also emission chromaticity also deteriorates decreases. The content of A1 is 3 X 10- ⁵ against ZnS lg - ³ X 10- 3 g more preferred gesture et al good Mashiku be in the range of ^{5 X 10- 5 - 1 X 10-} 3 g of It is a range.

[0020] The green light emitting phosphor emits light having the following spectral characteristics by excitation with electron beams having different current densities. That is, in the emission spectrum obtained by exciting this green-emitting phosphor with an electron beam, the emission peak wavelength (denoted as Nnm) is 60 nm shorter than the wavelength (N-60) nm. When the area of the part is (O), the ratio of (O) to the area (M) of the entire emission spectrum is 1.6% or less. (0) Z (M) ≤1.6%

In the embodiment, it is desirable that the ratio power of the area (P) of the wavelength portion shorter than the wavelength (N—70) nm to the area (M) of the entire emission spectrum is 0.8% or less. . (P) / (M) ≤0. 8%

[0022] The phosphor according to the embodiment of the present invention is manufactured as follows. First, a predetermined amount of activator raw material is added to the phosphor base material, which is the phosphor matrix, and flux (flux) such as salt potassium salt or salt magnesium is added as necessary. Add these in the wet Mix.

[0023] Specifically, the zinc sulfate raw material is dispersed in ion-exchanged water to form a slurry, and the activator raw material and flux are added thereto and mixed by a stirrer in a conventional manner. The mixing time is set so that the activator is uniformly dispersed. Next, the slurry containing the phosphor material and the activator is transferred to a drying container such as a pad and dried in a drier by a conventional method to obtain a phosphor material. As activator raw materials, for example, copper sulfate is used for Cu, and aluminum nitrate is used for A1. It is also possible to use compounds other than these.

[0024] The phosphor raw material thus obtained is filled into a heat-resistant container equipped with a check valve together with appropriate amounts of sulfur and activated carbon. At this time, sulfur is mixed with the dried phosphor raw material and blender, for example, for about 30 to 180 minutes, and after filling this mixed material in a heat-resistant container, the surface is covered with sulfur. It is preferable to do. Furthermore, after the entire container is heated and sucked and degassed, oxygen remaining in the container and moisture adsorbed on the raw material are removed, and then the inside of the container is placed in a sulfide atmosphere such as a hydrogen sulfide atmosphere or a sulfur vapor atmosphere. Alternatively, maintain in a reducing atmosphere (eg, 3-5% hydrogen balance nitrogen atmosphere). Then, the phosphor material in the container is fired in these atmospheres.

[0025] Firing conditions are important in controlling the crystal structure of ZnS as a phosphor matrix. In order to obtain the target phosphor, it is desirable to set the firing temperature in the range of 800–1, 250 ° C. If the firing temperature is less than 800 ° C, ZnS crystal grains cannot be grown sufficiently. On the other hand, when the firing temperature exceeds 1250 ° C, coarse particles increase, which is not suitable for use. Force depending on the set firing temperature The firing time is preferably 30-360 minutes.

[0026] Next, the obtained fired product is washed with ion-exchanged water or the like, dried, and further subjected to sieving to remove coarse particles, if necessary. Photoconductor powder can be obtained.

[0027] The phosphor of the embodiment manufactured in this way has improved emission chromaticity, and in particular, the emission luminance and color purity under a high current density are high. Therefore, this phosphor is suitably used for a color display device using an electron beam having an acceleration voltage in the range of 5-35 kV as an excitation source, such as a color CRT or FED, so that high-definition and high-quality images can be achieved. Can be planned [0028] Next, a field emission display (FED) which is another embodiment of the present invention will be described.

[0029] FIG. 1 is a cross-sectional view showing a main configuration of the FED. In the figure, reference numeral 1 denotes a face plate, which has a phosphor layer 3 formed on a transparent substrate such as a glass substrate 2. This phosphor layer 3 has a blue light-emitting phosphor layer, a green light-emitting phosphor layer, and a red light-emitting phosphor layer formed corresponding to the pixels, and a light absorbing layer 4 成る made of a black conductive material is interposed between these layers. This is a separate structure. Of the phosphor layers of each color constituting the phosphor layer 3, the green light-emitting phosphor layer is composed of the green light-emitting phosphor of the above-described embodiment. Each of the blue light emitting phosphor layer and the red light emitting phosphor layer can be composed of various known phosphors. Each color phosphor layer can be formed by a known slurry method or printing method.

[0030] The blue light-emitting phosphor layer, the green light-emitting phosphor layer, the red light-emitting phosphor layer, and the light absorption layer 4 that separates them are sequentially and repeatedly formed in the horizontal direction. A portion where the phosphor layer 3 and the light absorption layer 4 exist is an image display region. Various patterns such as dots or stripes can be applied to the arrangement pattern of the phosphor layer 3 and the light absorption layer 4.

A metal back layer 5 is formed on the phosphor layer 3. The metal back layer 5 is made of a metal film such as an A 1 film, and reflects the light traveling in the rear plate direction, which will be described later, among the light generated in the phosphor layer 3 to improve the luminance.

In addition, the metal back layer 5 has a function of imparting conductivity to the image display region of the face plate 1 to prevent electric charge from being accumulated, and serves as an anode electrode for the electron source of the rear plate. Fulfill. In addition, the metal back layer 5 has a function of preventing the phosphor layer 3 from being damaged by ions generated by ionizing the gas remaining in the face plate 1 and the vacuum vessel (envelope) with an electron beam. In addition, the gas generated from the phosphor layer 3 during use is prevented from being released into the vacuum container (envelope), and the vacuum degree is prevented from being lowered.

[0033] On the metal back layer 5, a getter film 6 made of an evaporable getter material having a force such as Ba is formed. The getter film 6 efficiently adsorbs gas generated during use. [0034] The face plate 1 and the rear plate 7 are arranged to face each other, and the space between them is hermetically sealed via the support frame 8. The support frame 8 is bonded to the face plate 1 and the rear plate 7 by a frit glass or a bonding material 9 having a force such as In or an alloy thereof, and the face plate 1, the rear plate 7 and the support frame 8 A vacuum vessel is constructed as an envelope.

The rear plate 7 includes an insulating substrate such as a glass substrate or a ceramic substrate, or a substrate 10 having a force such as a Si substrate, and a large number of electron-emitting devices 11 formed on the substrate 10. These electron-emitting devices 11 include, for example, a field-emission cold cathode, a surface conduction electron-emitting device, and the like, and the surface of the rear plate 7 on which the electron-emitting devices 11 are formed is provided with wiring (not shown). That is, a large number of electron-emitting devices 11 are formed in a matrix according to the phosphor of each pixel, and wirings that cross each other (XY wiring) that drive the matrix-shaped electron-emitting devices 11 line by line. have. The support frame 8 is provided with a signal input terminal and a row selection terminal (not shown). These terminals correspond to the cross wiring (X-Y wiring) of the rear plate 7 described above.

[0036] When a flat plate type FED is increased in size, there is a risk of bending due to the thin and flat plate shape. In order to prevent such deflection and to provide strength against atmospheric pressure, a reinforcing member (atmospheric pressure support member, spacer) 12 is appropriately disposed between the face plate 1 and the rear plate 7. May be.

[0037] In this color FED, since the green light-emitting phosphor layer that emits light by electron beam irradiation is composed of the green light-emitting phosphor of the embodiment, display characteristics such as light emission luminance and color reproducibility are achieved. It becomes possible to improve.

Example 1

Next, specific examples of the present invention will be described.

[0039] Example 1

First, zinc sulphate (ZnS) lOOOg, 6.5 g of aluminum nitrate (Α1 (ΝΟ) · 9Η0) and sulfuric acid

3 3 2

Add copper (CuSO · 5Η 0) 0.6g with appropriate amount of water, mix well and dry.

4 2

It was. Appropriate amounts of sulfur and activated carbon were added to the obtained phosphor material and filled into a heat-resistant container with a check valve. Further, the entire container is heated to 150 ° C for deaeration, and this is reduced to a reducing atmosphere. Baking in an atmosphere (3-5% hydrogen-balance nitrogen atmosphere). The firing conditions were 950 ° CX 90 minutes.

[0040] Thereafter, the obtained fired product was sufficiently washed with water and dried, and further sieved to obtain a target green-emitting ZnS: Cu, A1 phosphor. The obtained phosphor was subjected to the characteristic evaluation described later.

[0041] Example 2

A ZnS: Cu, A1 phosphor was produced in the same manner as in Example 1 except that the firing temperature was 1050 ° C. The obtained phosphor was subjected to the characteristic evaluation described later.

[0042] Example 3

A ZnS: Cu, A1 phosphor was produced in the same manner as in Example 1 except that the firing temperature was 1100 ° C. The obtained phosphor was subjected to the characteristic evaluation described later.

[0043] Example 4

A ZnS: Cu, A1 phosphor was produced in the same manner as in Example 1 except that the firing temperature was 1150 ° C. The obtained phosphor was subjected to the characteristic evaluation described later.

[0044] Comparative Example 1

Zinc sulfate (ZnS) lOOOg, copper sulfate (CuSO · 5Η 0) 0.68g and aluminum nitrate (Al (

4 2

NO) · 9Η 0) 6.5g was added with an appropriate amount of water, mixed well and dried. Obtained

33 2

Appropriate amounts of sulfur and activated carbon were added to the phosphor material, and the mixture was filled in a quartz crucible, which was fired in a reducing atmosphere (3-5% hydrogen-balance nitrogen atmosphere). The firing condition was 970 ° CX60 minutes. Thereafter, the obtained fired product was sufficiently washed with water and dried, and further sieved to obtain a ZnS: Cu, A1 phosphor emitting green light. The phosphor thus obtained was subjected to the characteristic evaluation described later.

[0045] Comparative Example 2

A ZnS: Cu, A1 phosphor was produced in the same manner as in Comparative Example 1 except that the firing temperature was 1050 ° C. The obtained phosphor was subjected to the characteristic evaluation described later.

[0046] Comparative Example 3

A ZnS: Cu, A1 phosphor was produced in the same manner as in Comparative Example 1 except that the firing temperature was 1075 ° C. The obtained phosphor was subjected to the characteristic evaluation described later. [0047] Comparative Example 4

A ZnS: Cu, A1 phosphor was fabricated in the same manner as Comparative Example 1 except that the firing temperature was 1100 ° C. The obtained phosphor was subjected to the characteristic evaluation described later.

[0048] Comparative Example 5

A ZnS: Cu, A1 phosphor was fabricated in the same manner as in Comparative Example 1 except that the firing temperature was 1150 ° C. The obtained phosphor was subjected to the characteristic evaluation described later.

Next, phosphor layers were formed using the green light-emitting phosphors obtained in Examples 1 and 4 and Comparative Examples 1 and 5, respectively. The phosphor layer was formed by dispersing each green light-emitting phosphor in an aqueous solution containing polyvinyl alcohol to form a slurry, and coating the slurry on a glass substrate with a spin coater. The thickness of each phosphor layer was adjusted to ³ × 10 ” ³ mg / mm ³ (3 mg / cm ³ ) by adjusting the rotation speed of the spin coater and the slurry viscosity.

[0050] Then, the emission luminance and emission chromaticity of each phosphor film obtained were examined. Emission luminance, acceleration voltage 10kV to each phosphor film was measured by irradiating an electron beam current density 1 μ AZmm ^2. Each luminance was obtained as a relative value when the luminance of the phosphor film formed using the phosphor of Comparative Example 1 was 100. The emission luminance, emission chromaticity and emission spectrum were measured using SR-3 manufactured by Topcon as a measuring instrument.

[0051] Further, the ratio of the emission area on the short wavelength side caused by defects or the like to the total area of the measured emission spectrum was obtained. That is, in the emission spectrum shown in Fig. 2, the area of the wavelength shorter than the wavelength (N-60) nm is (0) and the wavelength (N-70) nm is 60 nm shorter than the emission peak wavelength (Nnm)! When the area of the shorter wavelength portion is (P), the ratios (OZM and PZM) of (O) and (P) to the total area (M) of the emission spectrum were obtained. These measurement results are shown in Table 1.

[0052] [Table 1] Luminance X value y value Luminous area Luminous area

Percentage of (%) Percentage of (%) 0

(N-60) nm (N-70) nm Example 1 108. 1 0. 291 0. 620 1. 36 0. 72 Example 2 106. 3 0. 257 0. 602 1. 56 0. 84 Example 3 98. 3 0. 232 0. 589 1. 59 0. 81 Example 4 95. 4 0. 201 0. 571 1. 54 0. 76 Comparative Example 1 100. 0 0. 292 0. 614 2. 1 0 72 Comparative Example 2 94. 8 0. 277 0. 605 2. 83 1. 72 Comparative Example 3 90. 7 0. 256 0. 585 2. 80 1. 70 Comparative Example 4 90. 2 0. 238 0. 577 2. 36 1. 41 Comparative Example 5 85. 3 0. 198 0. 559 2. 60 1. 71

[0053] From the results shown in Table 1, the graph shown in FIG. 3 was obtained. The relationship of y = 0.520x + 0.468 holds between the X value and the y value of the emission chromaticity of the phosphor film formed using the phosphor of Example 1-14. Example 1 The relationship of y = 0.585x + 0.443 is established between the X value and the y value of the light emission chromaticity of the phosphor film formed using the phosphor of No. 5. won. In addition, it was proved that the green phosphor of Example 1-14 was superior in color purity to the green phosphor of Comparative Example 1-15.

[0054] Next, the current density of the electron beam applied to the phosphor film was changed, and the change in the light emission characteristics was measured and evaluated. That is, the current density of the electron beam was changed from 1 μA / mm ² to 50 μA / mm ² for the phosphor films formed using the phosphors of Examples 1 and 4 and Comparative Examples 1 and 5. The emission luminance and emission chromaticity were measured in the same manner. The amount of change in chromaticity (X, y) before and after changing the current density was calculated as the color shift using the following formula.

[0055] Color misregistration amount = (A x ² + Ay ² )

[0056] Further, a γ characteristic (value) which is a current luminance characteristic was obtained. That is, as shown in FIG. 4, a graph of the luminance change according to the change in the current density was approximated by the equation luminance = Α (current density) 、, and the value of Β was calculated as the γ characteristic. These results are shown in Table 2. [0057] [Table 2]

[0058] From the results shown in Table 2, the phosphor film formed using the phosphor of Example 1-14 is compared with the phosphor film formed using the phosphor of Comparative Example 11-5. As a result, the amount of color misregistration was small and the light emission characteristics were excellent. Also, with respect to the γ characteristics, the phosphor film formed in Example 11-14 shows a high value at a particularly high current density and the luminance is higher than that of the phosphor film formed in Comparative Example 11-15. I found it to be good.

Industrial applicability

[0059] As described above, according to the phosphor for display device of the present invention, the efficiency of green light emission can be improved by suppressing the light emission itself on the short wavelength side with a high transition probability at a high current density. As a result, the color purity of the green phosphor can be increased. Therefore, by using such a phosphor as a green light emitting phosphor, it is possible to obtain a color display device such as a CRT or FED having high luminance and excellent display characteristics.

Claims

The scope of the claims

[1] general formula: ZnS: Cua, Alb (where, a and b are to zinc sulfide lg is a fluorescent substance ^{matrix, 1 X 10- 5 ≤a≤ 1 X} 10- 3 g, 1 X 10 — ⁵ ≤b≤ 5 X 10—indicating an amount in the range of ³ g, each of which is a green-emitting phosphor that has a composition substantially represented by) and emits light when excited by an electron beam. The area of the entire emission spectrum (M), where (O) is 60 nm shorter than the wavelength at which the maximum emission intensity is obtained (hereinafter referred to as the emission peak wavelength), The phosphor for a display device, wherein the ratio of (O) to is 1.6% or less.

[2] the general formula: ZnS: Cua, us in Alb, Te, a and b, with respect to zinc sulfide 1 g is a fluorescent substance ^{matrix, 3 X 10- 5 ≤a≤ 8 X} 10- 4 g, ^{^{3 X 10- 5 ≤b≤3 X 10- 3}} g display device phosphor according to claim 1, wherein the amount ranging characterized by exhibiting, respectively it.

[3] A method for producing a green light-emitting phosphor containing zinc sulfide as a base and Cu and A1 as activators,

A step of removing adsorbed moisture and oxygen from phosphor materials each including the phosphor matrix and an element constituting the activator or a compound containing the element; and the moisture and oxygen are removed. A method for producing a phosphor for a display device, comprising a step of heating and firing the phosphor material while maintaining the state.

4. The method for producing a phosphor for a display device according to claim 3, wherein the step of firing the phosphor material is performed in a sulfide atmosphere or a reducing atmosphere of 1 atm or more.

[5] A phosphor layer that includes a blue-emitting phosphor layer, a green-emitting phosphor layer, and a red-emitting phosphor layer, an electron source that emits light by irradiating the phosphor layer with an electron beam, and the electron source And an envelope for vacuum-sealing the phosphor layer,

The display device according to claim 1, wherein the green light emitting phosphor layer includes the phosphor for display device according to claim 1.